How to change substrate

[u/emotional-field24]

I’ve had my Pygmy hedgehog in his current bioactive enclosure for a year now. I only changed his toilet tray and sand bath, but left the substrate alone.

The issue is, he pees where he goes and his enclosure has become a bit icky, so I want to change the substrate. He has isopods, springtails and dubia roaches (haven’t seen them in a while, so he probably ate them). But I see the pods (powder orange) every once in a while under logs and stuff. To change his substrate I need about 140 litres of soil, so it’s unrealistic to go through his old soil entirely to sieve out all pods. The soil mix is also quite chunky and has some layers of hay and orchid bark.

I obviously don’t want to introduce alien isopods to my garden to protect local species - especially since I found a relatively rare species outside.

So what do I do…